NSUF 23-4571: Investigating the effect of solute segregation on defect recovery kinetics in reactor-irradiated Ti

The degradation of material properties with irradiation depends intimately on the formation and – most crucially – the evolution of defects. Across all length scales, the evolution of radiation damage is strongly dependent on temperature. Thus, it is vitally important to understand precisely how these defects evolve with temperature. Recent work investigating defect annealing in neutron-irradiated commercially pure Ti (as a surrogate for Zr) has revealed the presence of an additional recovery stage where the established model predicts only one. Atomistic simulations have revealed that the point defect induced glide of dislocation loops contributes significantly to the observed recovery. However, the impact of solute segregation on the mobility of dislocation loops remains unknown. We propose to conduct atom probe tomography (APT) of these exact samples to determine the elemental distribution of O, N, C, Fe in the material, as well as whether they segregate to dislocation cores previously confirmed to exist in prior TEM work. We will also perform XRD to obtain dislocation densities via peak broadening, and nanoindentation to obtain nanohardness and stiffness as a measure of mechanical properties. These data will provide key inputs into a planned modeling effort to determine the effect of solutes on dislocation loop migration in HCP metals. Nanoindentation will also determine the impact of TEM-invisible defects on hardening in irradiated Ti. This work will bridge the gap between prior simulations of pure Ti and annealing experiments on commercial alloys, and will thus validate the postulated recovery mechanism for metals irradiated at reactor-relevant temperatures.

Additional Info

Field	Value
Abstract	The degradation of material properties with irradiation depends intimately on the formation and – most crucially – the evolution of defects. Across all length scales, the evolution of radiation damage is strongly dependent on temperature. Thus, it is vitally important to understand precisely how these defects evolve with temperature. Recent work investigating defect annealing in neutron-irradiated commercially pure Ti (as a surrogate for Zr) has revealed the presence of an additional recovery stage where the established model predicts only one. Atomistic simulations have revealed that the point defect induced glide of dislocation loops contributes significantly to the observed recovery. However, the impact of solute segregation on the mobility of dislocation loops remains unknown. We propose to conduct atom probe tomography (APT) of these exact samples to determine the elemental distribution of O, N, C, Fe in the material, as well as whether they segregate to dislocation cores previously confirmed to exist in prior TEM work. We will also perform XRD to obtain dislocation densities via peak broadening, and nanoindentation to obtain nanohardness and stiffness as a measure of mechanical properties. These data will provide key inputs into a planned modeling effort to determine the effect of solutes on dislocation loop migration in HCP metals. Nanoindentation will also determine the impact of TEM-invisible defects on hardening in irradiated Ti. This work will bridge the gap between prior simulations of pure Ti and annealing experiments on commercial alloys, and will thus validate the postulated recovery mechanism for metals irradiated at reactor-relevant temperatures.
Award Announced Date	2023-06-01T08:58:28.97
Awarded Institution	None
Facility	None
Facility Tech Lead	Alina Zackrone, Gordon Kohse
Irradiation Facility	None
PI	Charles Hirst
PI Email	[email protected]
Project Type	RTE
RTE Number	4571